Buffett’s “favorite” bet, revisited: the low-cost S&P 500 index fund

Warren Buffett’s investing advice often sounds counterintuitive in a world of constant headlines. A new market-focused article revisits the argument that, for the average investor, Buffett’s favorite investment type is straightforward: a low-cost S&P 500 index fund held for the long term, rather than active stock picking that requires frequent decisions.

The piece ties that approach to everyday mechanics. It describes an index fund as a diversified way to own a broad slice of the U.S. stock market, and it highlights the role of costs, pointing to Vanguard’s S&P 500 ETF, VOO, as an example with a stated expense ratio of 0.03%. It also emphasizes Buffett’s preference for regularly investing through downturns, “thick and thin,” instead of waiting for the right moment.

Berkshire Hathaway’s own historical shareholder letters show that Buffett’s stance is not new. In his 2013 letter, Buffett wrote that the non-professional investor’s goal should not be to “pick winners,” and that the right way to participate is to own “a cross-section” of businesses. In the same letter, he explicitly endorsed a “low-cost S&P 500 index fund” as a way to achieve that aim.

Buffett went further in the same 2013 letter by describing instructions he left for a trustee overseeing his wife’s inheritance. His plan allocated most of the money to a “very low-cost S&P 500 index fund,” while reserving a smaller share for short-term government bonds, and he said he suggested Vanguard’s version. That guidance reflects more than a preference for a benchmark, it reflects a view that reducing complexity and fees can matter as much as, or more than, outsmarting short-term market moves.

The idea also connects back to how Berkshire Hathaway has operated for decades. Berkshire is not an index fund, it owns operating companies and a managed portfolio of publicly traded stocks. But Buffett’s advice to outside investors is aligned with a broader theme that has shaped Berkshire’s culture: build advantage where you can understand it, then let compounding and disciplined cost control do the heavy lifting over time.

Still, the Motley Fool article does not provide new details about Berkshire’s current investment mix, nor does it specify how Buffett’s index-fund recommendation should translate to Berkshire’s own portfolio decisions. It also does not discuss fund tax treatment for individual investors, or how an investor’s horizon and risk tolerance might change the practical choice between an ETF and a mutual fund.

The clearest takeaway for investors may be the emphasis on process rather than prediction. While Berkshire continues to evaluate businesses and markets through its operating and capital-allocation framework, Buffett’s public messaging suggests that for many savers, the most repeatable edge may come from holding a broadly diversified, low-fee index through volatility. The market question now is whether investors, advisors, and asset managers will keep treating cost and staying power as the baseline, even as market conditions shift.